This invention relates to a pollution control device for an internal combustion engine.
In order to reduce the emission of unburned hydrocarbons from the exhaust of an internal combustion engine it has been proposed to retard the spark under certain operating conditions. Generally the spark is retarded during idle or coast periods when intake manifold vacuum is at its highest. This retardation is provided in a variety of manners but generally is accomplished by blocking off the communication of the vacuum advance circuit of the distributor from the portion of the induction system posterior to the throttle valve. Although this method is effective in reducing the amount of unburned hydrocarbons in the exhaust constituents under certain conditions, the retardation of the spark reduces performance both in terms of gas milage and accelleration. The stumbling or hesitation upon accelleration with most new cars is directly attributable to the retarded spark.
It is, therefore, a principal object of this invention to provide a pollution control device for an internal combustion engine that operates to retard the spark under certain conditions but which provides more immediate response upon accelleration.
It is another object of this invention to provide an improved valve that controls the vacuum signal to the vacuum advance circuit of the distributor in an improved manner.
Another constituent of the exhaust gases which must be controlled to meet standards set by the Federal Government for nitrous oxide. A common method of controlling nitrous oxide is through the recirculation of exhaust gases through the induction system to reduce peak combustion temperatures. The degree of exhaust gas recirculation is controlled by a valve, generally called the EGR valve, which is also responsive to induction system vacuum. Again, these valves tend to operate in such a manner so as to reduce engine performance by providing rough off idle operation, poor accelleration and reduced gas mileage.
It is, therefore, another principal object of this invention to provide a pollution control system for an internal combustion engine in which more accurate control over the operation of the EGR valve is provided.
For many years the emission of undesirable constituents to the atmosphere from internal combustion engines has been reduced by discharging the crank case ventilating gases into the induction system rather than directly into the atmosphere. By discharging the crank case ventilating gases into the induction system, further combustion is possible, thus reducing the emission of undesirable constituents. Because the intake manifold vacuum varies significantly with engine operating characteristics and this variance is not related to the desired flow of ventilating air through the crank case, some form of regulating valve is employed in the conduit leading from the discharge of the crank case ventilating system to the engine induction system. These valves are normally vacuum responsive and provide an increased restriction to flow at increased intake manifold vacuums to control the flow of gases from the crank case to the induction system.
Yet another principal object of this invention is to provide an improved crank case ventilating valve that also provides a control vacuum signal for another component of the pollution control equipment of the engine.